Powderous materials which are to be tabletted or used in another way, do not have, a as rule, the correct flowing properties but are cohesive, and thus it is general practice to convert the powder into a granulate prior to use.
At the production of the granulate the powder is provided with a solvent, optionally containing a binding agent to the formation of a semi moist mass, which is then formed into agglomerates and is dried to granules, or if a suitable size of the agglomerate is obtained directly, is immediately dried to a suitable particle size which varied dependent on the intended use. Optionally, the granulate has to be crushed to obtain the right particle size and particle size distribution. The size may vary from some 100 .mu.m to 1.5 mm in diameter.
All products are, however, not suited for a treatment using a solvent and often an inert carrier has to be added to obtain a suitable granulation.
One way of obtaining a solvent free granulation is to add another powder having good binding properties, to compress the pulverulent mixture into tablets or briquettes and then to crush these into a suitable particle/granulate size.
It shall be noted that a coating with a melted or softened material is previously known. Thus it is known to introduce, into a fluid bed apparatus, a powder and a wax and to obtain a wax coating by increasing the temperature of the air used to be blown through the bed. It is also known to add a powder to a melt present in a vessel provided with a jacket, to allow the melt to stiffen, and to crush it to a suitable size. These processes, however, lead to high increases of temperature in the material to be treated for a long time.
A great problem within particularly the food, feed-stuff and pharmaceutical industry is to obtain products which can easily be wetted without forming lumps (agglomeration). Particularly, products which are either very hydrophilic or very lipophilic create problems. The hydrophilic compounds cause problems as they absorb water too soon and thus create lumps, which are almost impossible to break, and the lipophilic compounds cause problems as they just float on the top and not become wetted at all, and not become suspended either. Thus one wishes to create dry products which can be easily suspended in water such as those used in the production of dry mixes for bread, sauces, nutrients, soups, desserts, and others, as well as antacids, fibrous materials such as bulk agents such as guar gum powder, isphagula, oat bran, wheat bran, alginic acid, and other products.
Another requirement is that the particle size shall be as small as possible in order to obtain the best possible mixing properties with other pulverulent materials, which are present in a composition.
A further problem within said industries is to be able to distribute fat in a produce without creating a later problem at the mixing with a liquid, or because the fat is not uniformly distributed in connection with cooking, or other preparation.